Propeller



C. H. HAVILL Feels. 23, 1932.

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attorney Patented Feb. 23, 1932 UNITED STATES PATENT OFFICE lLINTON H. EAVILI, OF ORANGE, NEW JERSEY, ASSIGNOR T0 ECLIPSE AVIATION COR- IORATION, F EAST ORANGE, NEW JERSEY., A. CORPORATION OF NEW JERSEY PROPELLER iapplication mea much 15, 1930. serial No. 436,186.

This invention `relates to propellers, and more particularly `to a propeller of the type adapted for use on aircraft.

There have heretofore been provided, for use on aircraft, hollow metal propellers which though possessing the advantage of being light in weight, have nevertheless certain disadvantages which include fatigue failures, excessive vibration and deflection, and noisy operation when the propeller 1s rotating at normal speed. It is accordingly one of the objects of the present invention to provide a hollow metal propeller, so constructed as to overcome the above diiiiculties and one which is particularly adapted for use on aircraft, where strength and lightness in weight are of great importance.

Another object of the present invention is to provide novel reinforcing means for the blades of a hollow metal propeller.

A further obj ect is to provide in a propeller blade of the above character, novel means for causing an initial compression to exist in the libres of the outer faces of the blade.

Another object is to provide in a hollow metal propeller blade, novel tension means for obtaining an initial distribution of stresses in the component parts of the blade.

A still further object is to rovide in a metal propeller, novel meansa apted toco- .act with the shell of the blade to resist the tension load due to centrifugal force when the propeller is rotating.

Other objects and novel features of the i invention will be more readily understood from the following detailed description of the invention when taken with the accom panying drawings which are illustrative of one form in which the invention may be embodied. It is to be expressly understood however that the drawings are for purposes of illustration only, and are not designed as a definition of the limits of the invention, reference. being had for this purpose tothe claims appended hereto. l y

In the drawings wherein similar reference characters refer to like several views:

Fig. 1 is a plan view of a propeller blade constructed in accordance with the present parts throughout the invention, a portion of the camber face half of the blade being cut away trate the thrust face half;

Fig. 2 is a perspective view of the two halves of the blade prior to final assembly thereof;

Fig. 3 is an enlarged longitudinal section taken through the root end of a finished blade;

Fig. 4 is an end view of the parts shown in Fi 3; and

ig. 5 illustrates one form of anchor which may be employed to connect the `tension members, such as wires or small rods, to the blade halves.

In the illustrated embodiment .of the invention there is shown a propeller blade comprising two halves which after being treated in a manner to be more specifically described hereinafter, are suitably secured together a? to form the finished blade'.

According to the present invention, each half of the propeller blade hasy secured to its inner surface at suitable spaced intervals, aY plurality ofx/members, such as wires, which are assembled so as to be initially under tension. As will be more specifically set` forth hereafter, `this construction im oses an initial stress in compression on the Ebres of the' outer faces of the propeller blade which serves to counteract or offset a portion in order to illusdjacent the meeting edges thereof of the tension load on the propeller caused stood that the blade operates well within the limits of fatigue strength. a i

Y:Referring more .particularly toFigls. 1

and 2, the propeller blade preferably comprises a pair of coactingkblade halves or shells 6 and 7 constituting respectively the thrust and camber face halves of the blade. These outer shells may be initially stressed by a plurality of interiorly disposed wires, or other suitable members, and the shells may be thereafter suitably secured together adjacent their meeting edges to form a hol low metal propeller blade which is not only light yin weight, but which is capable of successfully withstanding the various forces imposed thereon during operation.

As shown, the shells 6 and 7 are constituted by an outer member 8, on the interior surface of which a plurality oi anchors or cleats 11, Fig. 5, are suitably secured as by means of spot lwelding, said anchors being provided for receiving the looped ends of wires 12 constituting the internal strengthening and reinforcing members. These wires are pref*- erably assembled in such a manner that they will initially be under tension.

In the form of the invention illustrated, each of the shells 6 and 7 is provided with internal laminations 13 and 14 respectively, which may be assembled under initial tension with respect to the outer members 8, or they may be secured to said members in the `usual manner, that is, without the utilization of initial tension. It is also to beunderstood that these laminations may be omitted entirely, if desired.

After a suitable number of the anchors 11 have been secured at spaced intervals tothe inner surface of each of the blade halves, a plurality of wires 12 are threaded through the raised portion of each of the anchors, the ends of said wires extending outwardly from the root ends of each of said shells, as indicated in Fig. 1. Each of the blade halves are then placedin coacting relation with each other, that is, in such position' that the marginal edges of the -carnberface half will be aligned with the corresponding edges of the thrust face half.

Means' are provided for applying tension to the wires 12 and for securing the ends of said Wires in position in the root end of the blade while maintaining said tension. To this end, an outwardly tapered hub sleeve 15, provided with shear shoulders 16 and 17, Fig. 2, is first slipped over the root ends of the two shells 6 and 7 and the inner ends of said shells are outwardly flanged as at 18 and suitably secured to said sleeve as by means of a shield ring 19 and welded joint 20. A portion of the wire ends 12a, of wires 12 are adapted to be inserted through slots 21, Fig. 3, arranged in a cone wedge member 22, while the remaining wire ends 12" are maintained free of the wedge member, as indicated in Fig. .2. The blade is now held stationary in any suitable manner and a force in tension vapplied to each of the wires 12 by any suitable means, such as that indicated at 23. It is here pointed out, that as this force is applied to each of the wires, the shells 6 and 7 will become cupped or arched substantially as indicated in Fig. 2, if the shells have not been rigidly secured together along their meeting edges. J

While maintaining the tension on all of the wire ends, the wedge member is pressed inwardly to securely wedge the wire ends 12b between the periphery of said member and the flanged portion 18.v In order to secure the wire ends 12aL in position, tapered wedge blocks 24 are driven into the slots 21 which slots are outwardly tapered for receiving said blocks. The wire ends protruding from the member 22 may now be trimmed to a length sufiicient to allow them to be bent over into annular depressions 25 and 26 formed in said member. A circular locking plate 27 may be then secured, as by means of a screw 28, to the member 21, the being provided with annular ribs 29 and 30 adapted to cooperate with the de ressions 25 and 26 to firmly secure the en s of the Wires 12 in place.

In order to complete the blade, the shells 6 and 7 are pressed together from the position indicated in Fig. 2, to a position where the marginal edges thereof will be in abutting relationship throughout the remainder of their length. The shells are then welded or otherwise suitably connected together adjacent their meeting edges. It is here pointed l out that as the two blade halves are pressed together, the tension in wires 12 will be increased an'd the iibres of the outer members of each shell will be in a state of initial comression. If desired, the shells 6 and 7 may be Welded or otherwise connected together by suitable means before the wires are placed under tension.

During operation of a propeller embodying a plurality of blades constructed in accordance with the present invention, the forces in tension which will exist in each ot the blade halves will be substantially reduced, vdue to the initial compression thereof, which is eiective to offset or counteract a' portion of the tension load. Although the tension on the internal wire members will be increased during operation of the propeller, yet since this is the only force to which these members are subjected, the same may be readily designed to carry the necessary load.

There is thus provided by the present invention, a propeller blade of` novel construction, combining the characteristics of lightness 1n weight with great rigidity andv strength and one which is capable of successfully withstanding the various `:forces and components thereof encountered during rotation at high speeds. The stresses in the outer shell are initially in compression, due to the said plate internal wires under tension, and during oplll n ri.. w.

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eratiomthese stresses are only slightly in tension while the tension existing in the wire reinforcing members is materially increased. However, a sufcient number of these'wires may be employed to take care of the necessary forces. Since the outer shell, during operation, is relieved of a large portion of the tension load resulting from centrifugal force, fatigue failures of the blade will be less apt to occur, and the blade may more elliciently withstand torsional, thrust and other forces.

l/lhile there has been shown and described, one embodiment of the invention, it is to be understood that the invention is not limited thereto. l or example, the action of the wires under tension might be supplemented by one or more metal laminations under tension, if desired. Furthermore, the reinforcing members may be distributed in ways other than that indicated, it being necessary only that these members be located in such positions as to produce a sufficient torsional rigidity and accommodate a desired portion of the centrifugal load during operation of the propeller. Various other changes in the shapes, siZearelatir/'e location and manner of assemblying of the various component parts may be resorted to, as well understood by those shilled in the art, without departing' from the spirit of the invention as delined in the appended claims.

lll/"hat is claimed is:

l. A hollow metal propeller blade comprising a plurality of coacting shells, a plurality of interiorly disposed wires, means for connecting the outer extremities of .a number of said wires to one of said shells, means for connecting the remaining wires to another of said shells independently of said first-named connecting means, and means for maintaining said wires under tension.

2. A metal propeller blade comprising two coacting and rigidly connected shells, each of said shells including an outer member and a plurality of inner wires, means for connecing said wires to said outer member at points spaced longitudinally of said outer member, means for placing said wires under tension, and means for maintaining said tension.

3.` ln a hollow metallic propeller blade, means for placing the libres of the outer faces of said blade initially in compression, said means including a plurality of internal wires initially under tension, and means for connecting one end of said wires to said outer faces at points spaced longitudinally therealong.

4. A hollow metal propeller blade comprising two shells, each shell including on outer face, means for maintaining the libres of said outer face initially in compression, said means comprising a plurality of wires, and means for separately connecting said wires to each of said shells at points spaced longitudinally thereof,

5. A hollow metal propeller blade comprising two coacting shells, each shell including an outer member, and a plurality of inner wires separately connected to the outer member of each shell, and means for maintaining the said wires under tension while said propeller blade is stationary.

j 6, A propeller blade of the hollow metal type having a plurality of interiorly disposed wires under initial tension, said wires being connected to said bladey at longitudinally spaced portions. f

- 7. ln a propeller blade, means for initially causing compression of one of the outer faces thereof comprising a plurality of wires each of said wires being connected at'one extremity thereof to longitudinally spaced portions/of said face, means for placing said wires under tension, and means for securing said wires adjacent their other extremities to said face.

8. A hollow metal propeller blade comprising a pair of coacting shells, a plurality of longitudinally spaced anchorssecured to the inner surfaces of each of said shells, a wire looped around each anchor, the ends of said wires extending into the inner ends of said shells, means for placing said wires under tension, means for securing said wires in place adjacent the inner ends of each of said shells, and means for securing said shells together.

9. A hollow metal propeller blade comprislill ing a pair of coacting shells, a plurality of wires extending longitudinally into each of said shells, means for securing the outer portions of said wires to said shells, means for wedging the inner extremities of said wires into position, and means for securing said shells together.

10. A hollow metal propeller blade comprising an outer shell having an outwardly flared root end, a plurality of wires within said shell and connected thereto, means for placing said wires under initial tension, and means for wedging the ends of said wires into intimate contact with said flared root end of the shell.

1l. In a hollow metal propeller blade, means for placing the fibres of the outer faces thereof initially under compression including a plurality of interiorly disposed Wires, means for placing said wires under tension, and means for wedging the inner ends of said wires into position adjacent the root end of the blade.

l2. In combination with a hollow propeller blade shell, a plurality of tension members anchored to the root of the blade and also to the inner surface o`f the blade at pomts distant from said root and spaced lorf- A gitudinally along the inner surface of the lade, said tension members being free o 13. A hollow metal propeller the remaining intermediate portions of said shell. blade comprising a ps1-i1l of coacting shells, a plurality of wires extending into each of sald shells, means for securing the outer portions of said wires to said shells, an apertured wedge member cooperating with the inner ends of each of said shells and adapted to receive the inner ends of a portion of said wires, and means for wedging the ends of said wires in said apertured wedge. v

In testimony whereof I have signed this specification.

CLINTON H. HAVILL. 

